South Hadley is a town in Hampshire County, Massachusetts, United States. The population was 17,514 at the 2010 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area.
South Hadley is home to Mount Holyoke College, South Hadley High School, Pioneer Valley Performing Arts Charter Public School, and the Berkshire Hills Music Academy.

South Hadley is located in the western part of Massachusetts, specifically in the Pioneer Valley. It is bordered on the north by Hadley and Amherst, on the east by Granby, and on the south by Chicopee. The Connecticut River defines the town's western border and separates it from the city of Holyoke. South Hadley is 45 miles (72 km) south of Brattleboro, Vermont, 87 miles (140 km) west of Boston, and 145 miles (233 km) from New York City.

As of the census[17] of 2000, there were 17,196 people, 6,586 households, and 4,208 families residing in the town. The population density was 971.0 people per square mile (374.9/km˛). There were 6,784 housing units at an average density of 383.1 per square mile (147.9/km˛).